fix vendor

Author: lunny

vendor/modules.txt

@@ -444,6 +444,7 @@ go.mongodb.org/mongo-driver/bson/bsoncodec
 go.mongodb.org/mongo-driver/bson/bsonrw
 go.mongodb.org/mongo-driver/x/bsonx/bsoncore
 # golang.org/x/crypto v0.0.0-20190829043050-9756ffdc2472
+# golang.org/x/crypto v0.0.0-20190820162420-60c769a6c586
 golang.org/x/crypto/acme/autocert
 golang.org/x/crypto/argon2
 golang.org/x/crypto/bcrypt